Advancements in CT Three-Dimensional Reconstruction of Rock Samples

Nuclear magnetic resonance (NMR) relaxation and imaging are shown to give information on the changes of the pore space structure in ceramics during the sintering process. On a set of ceramic samples held at fixed maximum firing temperature of 1280 °C for different lengths of time, called “soaking times” in the ceramics industry, NMR methods were applied to quantify pore space properties such as connected porosity and pore size distributions. The longer the soaking time the lower the connected porosity, but no corresponding general statement can be made with regard to the pore size distribution. The homogeneous distribution of pores where the porosity is 17% for minimal soaking times becomes heterogeneous and with bigger pores but with porosity only about 5% after 10 min of soaking time. The results obtained are combined with those from traditional techniques such as scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). The measured connected porosities and SEM analysis are in agreement with the NMR results. The “pore size” distributions obtained by magnetic resonance relaxation and MIP differ substantially and give complementary information, because in relaxation measurements “size” tends to correspond to pore dimensions, while in MIP “size” corresponds to the dimensions of the pore “throats,” the channels connecting the pores. The discrepancy between pore and pore-channel size increases with the soaking time and makes it clear that a higher level of sintering allows the formation of larger pores connected by smaller channels. For the longest soaking time sample, the SEM photos and the lack of a NMR signal make it clear that there is substantial isolated porosity and essentially no connected porosity.

On the basis of the complexity of the pore structure characteristics of a coal reservoir, coal samples with different ranks were selected to study the difference in pore structures and permeability using nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and permeability measurement. Porosity and pore size distribution (PSD) above 20 nm can be analyzed by the improved NMR equation, and the results were basically consistent with that of SEM and MIP. The NMR spectra of the coal samples from the same location were close, but the difference between the coal samples from different locations was quite large, which indicated that the heterogeneity of a coal reservoir was strong. An empirical equation of movable fluid porosity was proposed, which can be used to evaluate the fluid migration characteristics of the coal reservoir, and the porosity of movable fluid mainly came from the contribution of fissures and micro-fissures. The average movable fluid porosity of the coal samples from the Chengzhuang (CZ) coal mine, Wuyang (WY) coal mine, and Yujialiang (YJL) coal mine was 1.37%, 0.67%, and 4.26%, respectively. Although the permeability is related to the NMR porosity and movable fluid porosity, it was difficult to establish a widely used mathematical equation correlating permeability and porosity based on the experimental data.

Understanding water retention and pore structure in concrete is essential for modeling unsaturated flow and assessing long-term durability, particularly in containment and deep foundation structures. This study investigates two concrete mixtures with different water-to-cement (w/c) ratios (0.40 and 0.50) using a multi-method approach. Water retention curves (WRCs) were measured with a chilled-mirror dewpoint potentiometer and fitted using the Fredlund–Xing model. Pore structures were analyzed via mercury intrusion porosimetry (MIP), X-ray computed tomography (CT), and scanning electron microscopy (SEM). Results show that the mixture with the lower w/c ratio exhibits a higher proportion of fine pores, while the higher w/c ratio leads to a broader pore size distribution and a flatter WRC. MIP-based WRC estimations provided a rough approximation but consistently underestimated measured retention values. CT and SEM revealed distinct pore size domains, with pore size distributions fitting better to a lognormal model than to a Weibull distribution. Although each technique offers only partial insight, their combined application allows for a more comprehensive understanding of concrete's pore network and its effect on hydraulic behavior. The findings highlight both the potential and the limitations of using indirect pore structure data to estimate water retention characteristics in cementitious materials.

Computed Tomography: Physical Principles and Recent Technical Advances

Ventral hernias are a surgical challenge, often requiring detailed imaging for surgical planning. Computed tomography (CT) is widely used in preoperative assessment, with three-dimensional (3D) reconstructions increasingly applied in surgical fields. This study aims to assess whether 3D CT reconstructions improve surgical planning compared to conventional two-dimensional (2D) CT. A cross-sectional survey was conducted from October 2024 to January 2025, enrolling 66 surgeons with diverse experience. Participants were randomized into two groups: one assessing a complex ventral hernia using conventional CT and the other using both 2D and 3D reconstructions. Data were collected through questionnaires based on the DECOMP criteria, surgeons' perception of hernia characteristics, surgical planning, and treatment strategies. Statistical analyses, including Fisher's exact test, Chi-square test, and ROC curve analysis, were performed to compare outcomes. No significant differences were found between the groups in the evaluation of the hernia, preoperative planning, or surgical approach. Surgeons predominantly relied on personal interpretation of CT scans rather than radiology reports. Notably, 3D reconstructions decreased the perception of hernia sac omental content (74.2% vs. 97.1%, p = 0.01). Furthermore, 3D visualization did not alter surgical decisions, including mesh selection, component separation, or preoperative techniques for loss of domain. 3D CT reconstructions do not impact the evaluation or surgical planning of complex ventral hernias compared to 2D CT. Although 3D imaging may enhance anatomical visualization, its clinical utility is unclear. Conventional 2D CT, when carefully analyzed, remains sufficient for surgical decision-making. Further research is needed to assess 3D imaging's benefits.

The pore characteristics of coal are highly correlated with gas permeability. In this study, multifractal analysis based on mercury intrusion porosimetry (MIP) was used to investigate the pore spatial distributions and heterogeneity of pore size distributions (PSDs) of three sister coal samples collected from the Xin Zhouyao mine in China. The mercury intrusion data, under pressures of over 10 MPa, were corrected in combination with the gas adsorption results. All CT images were processed by using the Image-Pro Plus® (IPP) software (Media Cybernetics, Inc., Rockville, MD). The pore volume percentage information obtained from the MIP was found to be coincident with the 3D reconstructions. Seepage experiments were also carried out under different gas pressures to analyze the effect of the pore parameters on permeability. The results from these experiments showed that for the three coal samples, the degree of clustering of the pores is the dominant factor for permeability and should be the first factor considered. Variations of μ (q, ϵ) versus ϵ indicated that the PSDs of coals have multifractal behavior. Multifractal analysis was suggested by the extracted parameters from the PSDs, including the capacity dimension D0, the information dimension D1, the correlation dimension D2, the widths of the right side D0–D10, and of the left side D−10–D0 of Dq spectra, and the widths of left side α0–αq+ and right side α0–αq− of the f (α) spectrum. These parameters were further discussed to evaluate the permeability.

Volcanic rocks are unconventional oil and gas reservoirs, and the pore structure of the rock is relatively complex. In this study, we selected samples from CS105 well and DS9 well from Yingcheng Formation volcanic reservoirs in the southern Songliao Basin to study the pore structure. First, we performed experiments on two rock samples using computed tomography (CT), and then measured the porosity and density of the two rock samples using mercury intrusion porosimetry (MIP). According to the data obtained by micron computed tomography (Micro-CT), Avizo 2019.1 software was used to perform three-dimensional (3D) reconstruction on the micron level of the two wellhead samples. Analyze the microscopic pore structure of the rock sample and compare it with the porosity of the sample obtained by the mercury injection method. Compared with MIP, Micro-CT more accurately characterizes the pore structure and porosity of volcanic rocks.

Synthetical study on the difference and reason for the pore structure of the No. 3 coal reservoir from the southern Qinshui Basin, China, using mercury intrusion porosimetry, low-temperature N2 adsorption, low field nuclear magnetic resonance, and nuclear magnetic resonance cryoporometry

Breast volume estimation from systematic series of CT scans using the Cavalieri principle and 3D reconstruction

An optimal protocol for clearing the cervical spine in unconscious patients with traumatic brain injury remains controversial. Protocols include plain radiographs and computed tomography (CT), and ligamentous injury may be identified with flexion-extension radiographs. We questioned whether cervical CT with three-dimensional (3D) reconstructions may obviate the need for flexion-extension radiology in the detection of occult ligamentous injury. Between July 1999 and November 2001, 276 unconscious traumatic brain injured patients admitted to The Alfred Hospital received cervical spine plain radiographs, CT with 3D reconstructions, and dynamic flexion-extension X-ray studies with fluoroscopy as part of a routine protocol. These patients were identified from a prospective intensive care unit database and all radiology reports were reviewed. Dynamic flexion-extension X-ray studies with fluoroscopy identified no new fractures or instability; there were no instances of true-positive results. Dynamic flexion-extension was true-negative in 260 of 276 (94%) patients, falsely positive in six patients (2.2%) and falsely negative in one (0.4%) patient. In nine patients, dynamic flexion-extension was inadequate. Dynamic flexion-extension X-ray studies with fluoroscopy delayed cervical spine clearance and were almost always reported as normal. In a cervical spine clearance protocol for unconscious traumatic brain injury patients, dynamic flexion-extension X-ray studies with fluoroscopy did not identify any patients with cervical fracture or instability not already identified by plain radiographs and fine-cut CT (C0 to T2) with 3D reconstructions.

A comprehensive method for studying pore structure and seepage characteristics of coal mass based on 3D CT reconstruction and NMR

3D reconstruction of the ribs from lateral and frontal X-rays in comparison to 3D CT-scan reconstruction

IntroductionPulmonary segmentectomy, when combined with hilar and mediastinal lymphadenectomy, is currently considered the gold standard treatment for early-stage lung tumors (NSCLC) smaller than 2 cm in diameter. The preoperative planning for segmentectomies usually includes a contrast-enhanced CT with 2D reconstructions (axial, coronary, and sagittal). Recent technological advances allow 3D (volume rendering) reconstructions of preoperative CT scans, intended to improve the surgeon’s understanding of the segmental anatomy.The study aims to investigate the added value of 3D reconstruction in enhancing the surgeon’s understanding of anatomical structures, thus facilitating surgical planning and improving oncological outcomes.Methods and analysisThis is a prospective, randomized, controlled study.Patients will be randomized into two groups:1. Group 2D: the preoperative workup for these patients will consist of a contrast-enhanced chest CT with two-dimensional (2D) reconstructions (axial, coronary, and sagittal);2. Group 3D: the preoperative workup for these patients will consist of a contrast-enhanced chest CT with two-dimensional (2D) reconstructions (axial, coronary, and sagittal) and a 3D reconstruction (volume rendering) of the same chest CT employing dedicated software.The primary endpoints will be negative margin (R0) resection rate, resection margin (staple line-to-tumor distance), and thoracotomy conversions.We will use Fisher’s exact test for binary outcomes and Mann–Whitney U test for continuous outcomes. For subgroup analyses, we will use regression. Multivariable analyses will be based on logistic regression for binary outcomes and linear regression for continuous outcomes.Ethics and disseminationThe protocol and the model informed consent forms have been reviewed and approved by the ethics committee (N.: 1–2023) concerning scientific content and compliance with applicable research and human subject regulations.A Subcommittee on Publications was established to review all publications and report its recommendations to the steering committee. The anonymized participant-level dataset and statistical code for generating the results will not be publicly available.Trial registrationThe protocol was registered at ClinicalTrials.gov (ID: NCT05716815; Prospective rAndomized sTudy efficaCy tHree-dimensional rEconstructions Segmentectomy - Full-Text View - ClinicalTrials.gov). Jan 19, 2023.

Carbonate reservoir rocks are composed of complex pore structures and networks, forming a wide range of sedimentary facies. Considering this complexity, we present a novel approach for a better selection of coreflood composites. In this approach, reservoir plugs undergo a thorough filtration process by completing several lab tests before they get classified into reservoir rock types. Those tests include conventional core analysis (CCA), liquid permeability, plug computed tomography (CT), nuclear magnetic resonance (NMR), end-trim mercury injection capillary pressure (MICP), X-ray diffraction (XRD), thin-section analysis (TS), scanning electron microscopy (SEM), and drainage capillary pressure (Pc). We recommend starting with a large pool of plugs and narrowing down the selection as they complete different stages of the screening process. The CT scans help to exclude plugs exhibiting composite-like behavior or containing vugs and fractures that potentially influence coreflood results. After that, the plugs are categorized into separate groups representing the available reservoir rock types. Then, we look into each rock type and determine whether the selected plugs share similar pore-structures, rock texture, and mineral content. The end-trim MICP is usually helpful in clustering plugs having similar pore-throat size distributions. Nevertheless, it also poses a challenge because it may not represent the whole plug, especially for heterogeneous carbonates. In such a case, we recommend harnessing the NMR capabilities to verify the pore-size distribution. After pore-size distribution verification, plugs are further screened for textural and mineral similarity using the petrographic data (XRD, TS, and SEM). Finally, we evaluate the similarity of brine permeability (Kb), irreducible water saturation (Swir) from Pc, and effective oil permeability data at Swir (Koe, after wettability restoration for unpreserved plugs) before finalizing the composite selection. The paper demonstrates significant aspects of applying the proposed approach to carbonate reservoir rock samples. It integrates geology, petrophysics, and reservoir engineering elements when deciding the best possible composite for coreflood experiments. By practicing this workflow, we also observe considerable differences in rock types depending on the data source, suggesting that careful use of end-trim data for carbonates is advisable compared to more representative full-plug MICP and NMR test results. In addition, we generally observe that Kb and Koe are usually lower than the Klinkenberg permeability with a varying degree that is plug-specific, highlighting the benefit of incorporating these measurements as additional criteria in coreflood composite selection for carbonate reservoirs.

To study the three-dimensional (3D) reconstruction and the visualization simulation surgery of spleen based on the scanning data of 64-slice helical computed tomograph (CT). The original data of 64-slice helical CT of spleen was collected, and then the CT image sequences were segmented and automatically extracted using auto-adapted region growth algorithm, and were conducted with the segmented images by adopt self-developed image processing software for 3D reconstruction. Finally, the 3D models were imported into FreeForm Modeling System for modifying and smooth. And the visualization simulation surgery was performed before splenectomy. It was fast and effective to utilize auto-adapted region growth algorithm to conduct spleen image program segmentation; the reconstructed models were seen clearly and could reappear the structure of the spleen and the important surrounding organs. The effect of the splenectomy simulation surgery was similar to the practical surgery. The research on 3D models of spleen and visualization simulation surgery of splenectomy could lead to clinical benefits. It maybe improve the surgical effect and decrease the surgical risk and reduce the complication demonstrating visualized operation before surgery.